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Please refer to the GENERAL COMMENTS section of the letter for a discussion <br />of the present and future operation of Colowyo's sediment control ponds. The <br />CDMG has copies of all of Colowyo's hydrological modeling and the CDMG is <br />encouraged to review each modeling effort. Colowyo would be pleased to review <br />our pond hydrology/sedimentology models with the CDMG. <br />C. olo e to er ~ 1997 "Comments ~ Draft CDPES Permit and Rationale" <br />The only relevant columns in the table are "outfall", "wastewater source", and <br />"receiving water."e <br />Please refer to the General Comments of this letter for a discussion of the present <br />and future operation of Colowyo's sediment control ponds. The CDMG is correct <br />that under the containment scenario which Colowyo currently operates its' ponds, <br />dischazges from the manually operated headgates have not been designed to meet <br />any effluent limitation. <br />2. Colowyo has precipitation induced water that enters the upper mine benches in the <br />mining area and subsequently rrrtts out of the mining azea and into sediment <br />control ponds. Colowyo also has water that enters the bottom of a mine <br />production pit and pools which may require mechanical removal via pumping. <br />Colowyo was clarifying that when waters have to be mechanically pumped out of <br />amine production pit, additional consideration is necessary to evaluate the <br />appropriate effluent limitations and associated permit conditions. <br />The removal of the words "process water" more accurately reflects the true <br />operating conditions at the Colowyo mine. Most of the water in a mine <br />production pit is precipitation-induced surface runoff and, categorically, not <br />process water. The only "process water" that Colowyo generates is vehicle wash <br />water. Surface runoff that ends up in a mine production pit is still considered <br />surface runoff, as cleazly set forth in the Rationale to the General Petmit No. <br />COG-850015 for coal mining dischazges, and the subject of more discussion in <br />the Mazch 6, 1996 letter to WQCD from Colowyo's counsel, D. Kennedy. <br />4. The language in the new draft WQCD Rationale document dated August 1 I, <br />1997, incorrectly reflects the permit application. The permit application <br />requested that Colowyo identify chemicals that will be added to the water as a <br />BLetter to J. Kubic from K. Wolf, dated September, 30, 1997 <br />